A Study of the Nucleon Spin Structure in Strong and Electromagnetic Interactions Dubna-Protvino-Prague-Moscow-Mainz-Glasgow-Los Angeles-Basel-Edinburg-Zagreb-Pavia-Lund- Kharkov-Bochum S.B. Gerasimov Project «GDH» & «SPASCHARM»

Experiments with Polarized Targets and Beams. Projects ”GDH” & ”SPASCHARM” Dubna, Dzhelepov Laboratory of Nuclear Problems, JINR N.A. Bazhanov, N.S. Borisov, A.N. Fedorov, I.V. Gapienko, V.A. Kalinnikov, A. Kovalik, E.S. Kuzmin, A.B. Lazarev, G.I. Lykasov, A.B. Neganov, I.L. Pisarev, Yu.A. Plis, S. Prakhov (UCLA), A.A. Priladyshev, A.B. Sadovski, S.N. Shilov, Yu.A. Usov, Dubna, Flerov Laboratory of Nuclear Reactions, JINR M.P. Ivanov Dubna, Bogoliubov Laboratory of Theoretical Physics, JINR S.B. Gerasimov, S.S. Kamalov Protvino, Institute for High Energy Physics V.V. Mochalov, A.N. Vasiliev, N.I. Belikov, V.N. Grishin, A.M. Davidenko, A.A. Derevscikov, V.I. Kravtsov, Yu.A. Matulenko, Yu.M. Melnik, A.P. Meshanin, S.B. Nurushev, A.F. Prudkoglyad, L.F. Soloviev, A.E. Yakutin Prague, Charles University J. Brož, J. Černy, Z. Doležal, P. Kodyš, P. Kubik J. Švejda, I. Wilhelm Prague, IEAP, CTU F. Lehar, S. Pospišil, M. Solar Moscow, Institute for Nuclear Research, Russian Academy of Science G.M. Gurevich, R.L. Kondratiev Mainz, Institut für Kernphysik H.-J. Arends, M. Martinez, A. Thomas, E.-P. Schilling, M. Ostrick Glasgow, Glasgow University, Los Angeles, University of California, UCLA, Basel, Institut f¨ur Physik, Edinburg, Department of Physics, University of Edinburg, Zagreb, Rujer Boskovic Institute, Pavia, Sezione di Pavia, INFN, Lund, MAX-lab., Lund University, Kharkov, Kharkov Institute of Physics and Technology, Bochum, Institut für Experimentalphysik Ruhr Universität Leader of the ProjectA.Kovalik, Yu.A. Usov Deputies of the LeadersS.B. Gerasimov, I.L. Pisarev

Strong Interactions (IHEP, Protvino) Goals: Study of single-spin assymetry based on large statistics of the production of light meson resonances (ρ, ω etc) Study of spin effects in charmonium production to understand charmonium hadronic production mechanism and to extract gluon polarization Δg(x) at large x

Strong Interactions Experiments: Measurement of single-spin asymmetries in the production of miscellaneous light resonances with the use of 34 GeV π - beam Measurement of single-spin and double-spin asymmetries in charmonium production with the use of 70 GeV polarized proton beam

Strong Interactions Equipment: U70 accelerator at Protvino Unpolarised π - beam; E = 34 GeV Polarized proton beam; E = 70 GeV Large frozen spin proton target at Protvino

SPASCHARM experimental setup

First stage (unpolarized beams) A study of the single spin assymetry AN of light resonances consisted of u-, d- and valence quarks. Inclusive and exclusive reactions will be studied simultaneously. The errors in the exclusive reactions with big asymmetries are expected to be several times less than now.

Second stage (polarized beams) The goal of the proposed experiment is to measure double-spin asymmetry ALL with the use of longitudinally polarized beam and target in the process: p → + p → → χ c2 (J/Ψ) + X, (χ c2 → J/Ψ + γ). The measured experimental asymmetry is given by where P B is the beam polarization, P T eef is the effective target polarization, I ++, I +− are the number of events normalized to the incident beam

Electromagnetic Interactions (Mainz, A2-collaboration) Motivation Equipment Experiments

hadron-spinphoton-spinhadron-spinphoton-spin aa pp Anomalous magnetic moment 1) Experimental verification of the GDH sum rule  Proposed in 1966  Prediction on the absorption of circularly polarized photons by longitudinally polarized hadrons

More detailed information on resonance properties and multipole amplitudes by investigating the helicity structure of partial reaction channels More detailed information on resonance properties and multipole amplitudes by investigating the helicity structure of partial reaction channels Main goals: single   - production (D 13 (1520), F 15 (1680))  - production ( S 11 (1535), D 13 (1520 )) double   - production (D 13 (1520), P 11 (1440), P 11 (1710)) 2) Helicity Dependence of Meson Photoproduction

MAINZ MICROTRON continuous polarized electron beam, E=1.5 GeV, Pe=85%

Glasgow-Mainz Photon Tagger

Polarisation transfer from electron to photon beam as a function of energy transfer

A2 DETECTOR SETUP Because of its high-granularity and large acceptance the CB/TAPS setup is a suitable detector system for measurements of reactions with multi-photon final states like in π 0 → 2γ, η → 2γ or η → 3π 0 → 6γ

I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95, 347 (1975). 4 Complex amplitudes - 16 real polarization observables. A complete measurement from 8 carefully chosen observables.

First experiment: Transverse asymmetries T and F in π 0 and η photoproduction Physics motivation: Measurement of the target asymmetry T and the double-polarisation observable F in order to investigate interference effects between the S 11 (1535) and the D 13 (1520) nucleon resonances and to determine the energy-dependent phase shift between s and d waves, which is not yet taken into account by isobar models (MAID, SAID) for η photoproduction. Equipment: A beam of circularly polarised photons, energy-tagged by the Glasgow- Mainz tagging system, in combination with a transversely polarised 'Frozen Spin' butanol target. The reaction products are detected using the Crystal Ball / TAPS 4π photon spectrometer; the PID detector and the cylindrical wire chambers perform particle identication and track reconstruction for charged particles.

The cross section for single meson production in case of a transversely polarised target and a circularly polarised photon beam As the target asymmetry T is a single polarisation observables, it is accessible with only a polarised target and an unpolarised photon beam. However, using a circularly polarised photon beam does not affect this asymmetry but gives also access to the double-polarisation observable F. The target asymmetry T can be extracted integrating over both helicity states of the incoming circularly polarised photons, which eliminates any contributions from F.

The helicity dependent total cross section for semiexclusive channels a) γd → π 0 X (X=pn or d) and b) γd → π ± NN (full circles) compared to our previous results (open circles) and to corresponding model predictions in the Δ-resonans region.

Helicity amplitudes in proton and neutron channels A 1/2 A 3/2 N*MAID2005SAIDPDGMAID2005SAIDPDG P 33 (1232) ± ± ± ± 8 P 11 (1440) ± 2-65 ± 4--- D 13 (1520) ± 2-24 ± ± 2166 ± 8 S 11 (1535)6630 ± 390 ± S 31 (1620)66-13 ± 327 ± S 11 (1650)3374 ± 153 ± D 15 (1675)1533 ± 419 ± 8229 ± 315 ± 9 F 15 (1680) ± 2-15 ± ± 2133 ± 12 D 33 (1700)22689 ± ± ± 785 ± 22 P 13 (1720)73-18 ± ± 20 F 35 (1905)182 ± 526 ± ± 5-45 ± 20 F 31 (1910)18-3 ± F 37 (1950) ± 4-76 ± ± 3-97 ± 10 P11(1440)5447 ± 540 ± 5--- D13(1520) ± 4-59 ± ± ± 11 S11(1535) ± 5-46 ± S11(1650)9-28 ± 4-15 ± D15(1675) ± 4-43 ± ± 5-58 ± 13 F15(1680)2829 ± 629 ± ± 9-33 ± 9 P13(1730)-3--1 ± ± 61

SUMMARY MAMI C: circularly and linearly polarized energy tagged photon beams up to 1.5 GeV FST: longitudinally and transversely polarized proton and deuteron targets Any combinations of beam and target polarizations are possible Detecting system Crystal Ball/TAPS: measurement of reaction products in 4π geometry PAC-2009 of CB-MAMI collaboration: 9 of 14 proposals – various double polarization experiments

SUMMARY The new polarization program SPASCHARM is being prepared in Protvino. Inclusive and exclusive reactions will be studied simultaneously. All the new data will much help us to understand spin dependence of strong interactions in the quark confinement region. The results on ∆g(x) at large x will be unique and complementary to those which exist and might be obtained at COMPASS, HERMES, RHIC and JLAB at smaller x.

1.5 K radiation shield 25 K radiation shield Separator (3K) and Evaporator (1.2K) precooling stages ( 4 He) 80 K radiation shield 3 He/ 4 He Dilution stage T min ≈ 23 mK Polarization ≈ 94% Relaxation ≈ 1500 hours ≈ ≈

Internal longitudinal Holding coil ( solenoid coil manufactured of μm multifilamental NbTi cable and consisting of four layers, each having 600 turns wound around a 0.3-mm thick copper holder, T ≈ 1.5 K)

Main parameters Working parameters of the dilution cryostat are in agreement with the technical requirements: - T min ≈ 23 mK; - polarization relaxation time ≈ 1500 hours (at T=30 mK); - time to cool from room temperature ≈ 5 hours; - LHe consumption in the frozen spin mode ≈ 2 l/hour Internal holding coils provide longitudinal/ transverse field 0.4 Tesla at 30 A Any combinations of beam and target polarizations are possible Two-part insert makes the sample loading operation easy and convenient Future development: New insert, containing light-guides, for active polarized target

Working plan 2011: − Design of the ”Active Target” (GDH). − First measurement of the spin asymmetry in meson photo production up to 1500 MeV using linearly polarized photon beam and transversely polarized proton target (GDH). − Measurement of the single-spin asymmetry AN of light reso nances consisting of u−, d− and s−valence quarks (SPASCHARM). 2012: − Measurement of transverse asymmetries T and F in η-photoproduction in the region of S11 (1535) resonance (circularly polarized photon beam and transversely polarized proton target) (GDH). − Manufacturing and tests of the ”Active Target” (GDH). − Measurement of AN for inclusive and exclusive reactions π p → ω(782)n and π − p → η (958)n (SPASCHARM). 2013: − Upgrade of the proton frozen spin target to the polarized deuteron variant. Measurement of the helicity dependence of single and double pion photoproduction processes and the GDH integral on the neutron (circularly polarized photons up to 1450 MeV and longitudinally polarized deuteron target) (GDH). − Experiments with the ”Active Target” (GDH). − Measurements of the single-spin asymmetry AN in charmonium production (SPASCHARM).

Form №26 Title of expense item Total cost Laboratory proposals for distribution of finances The modification of the UHF system of the polarized target Design and preparation of the parts of ”Active Target” Modification of the polarization measurement system Purchase standard devices TOTAL (equipment) Materials TOTAL Finance sources 1. Budget expenses: a) direct (immediate) b) Grants of Germany (BMBF) Total immediate expenses Out of budget financing a) Collaborator aid b) Grant (Russia) financing Proposed schedule and necessary resources for realization of the Project ”SPASCHARM-GDH” (k$) Leader of the ProjectA. Kovalik, Yu.A. Usov Deputies of the Leaders S.B. Gerasimov, I.L. Pisarev

Form №29 Title of expense item Total cost R & D agreement expenses Job cost in the LNP’s experimental shop Materials Transport expenses Unforeseen expenses Electronic instruments Travel expenses Inclusive a) to nonruble zone countries b) to ruble zone countries c) visits to JINR Total immediate expenses: Estimate of the expenses for the Project ”SPASCHARM-GDH” (k$) Leader of the ProjectA. Kovalik, Yu.A. Usov Deputies of the LeadersS.B. Gerasimov, I.L. Pisarev Director of the LaboratoryA.G. Olshevsky Leading engineer-economistO.N. Shestakova